Finite difference method solving boundary condition
이전 댓글 표시
Hi try to solve the nonlinear ordinary difference equation by finite difference method with boundary conditions: U(-1) = 0, U(1)=0. The code below.
Function [r, sol] =res(U)
n = 10;
r = ((1:n)-1)/(n-1);
r0=zeros(n+1,1);
color={'r','m','c','b');
For delta = 2:5
Sol = solve(@(r)fun(r, n), r0);
norm(fun(sol, n));
Plot(r, sol(1:n), color{delta-1});hold on;
end
legend('delta=2', 'delta=3','delta=4','delta=5');
Function res=fun(z, n)
lambda =0.1;
beta = 0.1;
eps = 0.1;
m=0;
r = ((1:n)-1)/(n-1);
h=1/(n-1);
U = z(1:n);
res_U = zeros(n, 1);
res_U(1)=0;
For i=2:n-1
res_U(i)=((1+beta*U(i))/h^2)*(U(i+1)-2*U(i)+U(i-1))+((1+beta*U(i))/(r*h))*(U(i+1)-U(i-1))+beta*((U(i+1)-U(i-1))/h)^2+lambda*((1+eps*U(i))^m)*exp(U(i)/(1+eps*U(i)))-delta*U(i);
end
res_U(n)=0;
res = res_U;
end
Outcome
>> res
Warning: Trust-region-dogleg algorithm of Fsolve can not handle non-square systems; using levenberg-marquardt algorithm instead.
Equation solved. Fsolve completed because the vector of function values is near zero as measured by the default value of the function tolerance, and the problem appears regular as measured by the gradient.
'Please help me correct this errors'
댓글 수: 5
Oluwaseun Adisa
2021년 5월 22일
Oluwaseun Adisa
2021년 5월 28일
Torsten
2021년 5월 28일
Is it necessary to write your own code ? If not, you should use sophisticated matlab code especially designed for this problem class, i.e. bvp4c in your case.
Oluwaseun Adisa
2021년 6월 5일
답변 (0개)
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